Jet engine burner apparatus having means for spreading the pilot flame



Feb. 10, 1959 H. E. BARRETT ETAL NG MEANS FOR SPREADING THE PILOT FLAME3 SheetsSheet 1 INVENTOREI HILLARD E. BARRETT: WILLIAM I PAYNE.

MM M

ATTORNEY Feb. 10, 1959 H. E. BARRETT ETAL 2,

JET ENGINE BURNER APPARATUS HAVING MEANS FOR SFREADING THE PILOT FLAMEFiled June 6, 1951 3 Sheets-Sheet 2 L Afl l l gz ETT HI L WILLIAM F1PAYNE.

ATTORNEY Feb. 10, 1959 H. E. BARRETT ETAL JET ENGINE BUR NER APPARATUSHAVING MEANS FOR SPREADING THE PILOT FLAME 3 Sheets-Sheet 3 Filed June6, 1951 v n z 0R5 HILLARD E. BARRETT BYWILLIAM F. PAYNE.

Zfi A. ATTORNEY United States Patent JET ENGINE BURNER APPARATUS HAVINGMEANS FOR SPREADING THE PILOT FLAME Hillard E. Barrett, East Orange, andWilliam F. Payne,

Cedar Grove, N. 3., assignors to 'Curtiss-Wright Corporation, acorporation of Delaware Application June 6, 1951, Serial No. 230,212

19 Claims. (Cl. fill-39.72)

This invention relates to combustion apparatus and is particularlydirected to combustion apparatus for jet engines.

The invention has been designed for use with jet engines in whichmaintenance of stable and eflicient combustion is diflicult particularlybecause of the high velocity of flow through the combustion chamber. Anobject of the present invention comprises the provision of means forquickly spreading a pilot flame over primary ignition apparatus forigniting the main combustion mixture. A further object of the inventioncomprises the provision of means providing flame flow paths for thecombustion flame to an annular secondary igniter structure disposeddownstream of said primary structure. A still further object of theinvention comprises the provision of combustion apparatus for a jetengine having a streamlined center body structure in which saidapparatus comprises a pilot burner disposed completely within saidcenter body structure and a cooling air flow path is provided betweenthe inner walls of said center body structure and said pilot burner.

Other objects of the invention will become apparent upon reading theannexed detailed description in connection with the drawing in which:

Fig. 1 is a schematic axial section through a ram jet engine embodyingthe invention;

Fig. 2 is an enlarged view of a portion of Fig. 1 taken along line 22 ofFig. 3;

Fig. 3 is an enlarged view taken along line 3 3 of Fig. 1;

Fig. 4 is a sectional view taken along line 4-4 of Fig. 2;

Fig. 5 is a view similar to Fig. 2 but of a modified form of theinvention and taken along line 5-5 of Fig. 6;

Fig. 6 is a view taken along line 66 of Fig. 5; and

Fig. 7 is a sectional view taken along line 77 of Fig. 5.

Referring now to Figs. 1-4 of the drawing, a ram jet engine isschematically indicated by reference numeral 10, said engine comprisingan open-ended duct 12. The duct 12 has a forwardly directed air entranceopening 16 and a streamlined center body 18 may be co-axially supportedwithin said duct adjacent to its forward end. Various auxiliaryequipment of the engine, as for example fuel and oil pumps and theircontrols, are generally supported within the center body 18. The duct 12also includes a combustion chamber 20 downstream of the center body 18and a nozzle 22 is provided at the rear end of the duct 12 through whichthe combustion chamber gases discharge to provide the power plant wtihforward propulsive thrust. Fuel is supplied through a plurality of fuelnozzles 24 to provide a main combustible mixture for ignition in thecombustion chamber 20.

The center body 18 has a streamlined outer periphery and a pilot burner26 is completely disposed therein at the downstream end of said centerbody. The pilot burner has a conical upstream end with a burner tube 28extending therefrom, said burner tube preferably having a reduceddiameter discharge end at the downstream end 2,872,785 Patented Feb. 10,1959 '30 flows over the pilot burner tube 28 through the annular passage34 and out the downstream end of the center-body. This latter air flowhelps cool the pilot burner tube.

Fuel is supplied to the pilot burner 26 through one or more fuel nozzles36. The pilot burner also has a flame holder means 38 disposed acrossthe upstream end of the pilot burner tube 28. As illustrated said flameholder means comprises a disc with a plurality of swirl slots 44]therethrough and a central opening through which extends a suitableigniter 42, such as a spark plug. Thus the pilot burner flame burns inthe tube 28 and discharges through the restricted downstream opening ofsaid tube. The enlarged diameter upstream portion of the pilot burnertube 28 provides a region of relatively low velocity thereby adding tothe stability of the pilot burner flame.

An annular channel member or gutter 44 is supported co-axially anddownstream of the pilot burner and center body. The annular gutter 44 isdisposed downstream of the center body 18 and the pilot burner 26 so asto minimize its drag effect on the fluid flowing through the duct 12.The annular gutter 44 has a V-shaped crosssection with the open side ofits annular channel facing in a downstream direction. A plurality ofcircumferentially-spaced linear channel members or gutters 46 extendfrom the pilot burner tube 28 through the center body 18 to the annulargutter 44. Four such linear gutters 46 are illustrated and each suchlinear gutter has one end opening into the pilot burner tube 28 and hasits other end opening into the annular gutter 44. The minimum radius ofthe annular gutter 44 is larger than the radius of the outer peripheryof the discharge end of the pilot burner tube 28 so that the lineargutters 46 diverge in a downstream direction. Each linear gutter 46 hasa generally V-shaped cross-section and the open channel side of eachlinear gutter faces in a generally inward and downstream direction sothat the combustible fluid flows over each said linear gutter from itsapex.

A second or secondary annular channel member or gutter 48 is co-axiallydisposed downstream of the first or primary annular gutter 44. Saidsecondary annular gutter 48 has a V-shaped cross-section with its openchannel side facing downstream and is disposed a substantial distancedownstream of the primary annular gutter 44, preferably axiallydownstream of a point at which the turbulence of the main combustiblemixture created by said primary gutter begins to fall 01f substantially.A second plurality of linear channel members or gutters 50 extend fromthe outer periphery of the primary annular gutter 44 to the secondaryannular gutter 48, said gutters 50, like the gutters 46, beingcircumferentially-spaced for flow of a portion of the combustiblemixture through the spaces between said gutters. One end of the channelof each of said second or secondary linear gutters is in communicationwith the channel of primary annular gutter 44 and the other end of thechannel of each of said secondary linear gutters is in communicationwith the channel of the secondary annular gutter 48. As illustrated, thesecondary gutter 48 has a minimum radius larger than that of theradially outer periphery annular gutter 44 so that the secondary lineargutters 50 diverge in a downstream direction. The magnitude of thisdivergence is small so that each secondary linear gutter 50 extends in agenerally downstream direction from the primary annular gutter 44. Inaddition each secondary linear gutter 50 has a V-shaped cross-sectionwith its open channel side facing inwardly. Thus the portion of thecombustible mixture flowing over the outer periphcry of the primaryannular gutter 44 and over the radially inner edge of the secondaryannular gutter 48 flows over each side of and between thecircumferentially-spaced secondary linear gutters 50.

The pilot-burner 26 is supplied with sufficient fuel such that burningpilot fuel is propagated or spread out through the primary lineargutters 46 to the primary annular gutter 44. The burning pilot fueldischarging from the pilot burner and propagated along the primarylinear gutters 46'to the primary annular gutter 44 is eflective toignite the main combustible mixture flowing thereover. The secondarylinear gutters 50 act to guide the flame of the burning combustiblemixture from the primary annular gutter 44 to the secondary annulargutter 48 whereupon the annular gutter 4% acts as a secondary source ofignition for the main combustible mixture downstream of the primaryignition at the pilot burner 26, linear gutters 46, and annular gutter44. It has been found that the addition of such a secondary annulargutter provides for smoother and more eflicient combustion. In additionsince the secondary gutter 48 is disposed close to the wall of thecombustion chamber 29 it tends to prevent the combustion flame fromflashing back upstream from said gutter along the wall of the combustionchamber. Furthermore by disposing the annular gutters 44 and 48 indiflerent transverse planes instead of in a single transverse plane theyoifer less drag resistance to the flow of the main combustible fluid.

As already stated, the secondary annular gutter 48 is disposed asubstantial axial distance downstream of the primary annular gutter 44whereby each secondary linear gutter 50 has a substantial length in anaxial direction. If each secondary linear gutter 50 makes no angle oronly a small angle with the axis of the combustion apparatus describedthen flame will be propagated therealong at a steady rate from theprimary annular gutter 44 to the secondary annular gutter 48. If,however, this angle is increased beyond a small value, for examplebeyond 10, then the flame propagated along each secondary gutter 50 willbecome unsteady, that is it will pulsate as a result of the turbulencecreated by the main combustible mixture flowing over said secondarylinear gutter. The frequency of said flame pulsations apparentlyincreases with an increase in said angle. A high frequency of pilotflame pulsation is not too objectionable since it appears to attenuateitself but a low frequency of pulsation of the pilot flame causes roughcombustion. The angle each secondary linear gutter 50 makes with theaxis of the combustion axis cannot be made large enough to avoid saidlow frequency flame pulsations since, as stated, the secondary annulargutter 43 should be disposed a substantial axial distance downstream ofthe primary annular gutter 44. Hence the angle between each secondarylinear gutter 5t] and said axis is made small It has been found that foran aircraft jet engine this angle should be no more than approximatelyand preferably is within the range'of 4 to 7.

At this point it should be noted that the primary linear gutters 46 makean angle of approximately 30 with the axis of the combustion apparatus,suflicient fuel being supplied to the pilot burner 26 for propagation ofa flame through said linear gutters 46 to the primary annular gutter 44.This angle of 30 is sufficiently large that the frequency of pulsationof the flame propagated along the primary linear gutters 46 is highenough not to be objectionable. As far as said pilot flame propagationis concerned the primary linear gutters 46 could be radial. With thislatter arrangement, however, the plane of the primary annular gutter 44would include the center body 18 and therefore the drag resistance ofsaid gutter would be increased.

If for some reason the quantity of fuel supplied to the central pilotburner 26 is insufficient to insure propagation of a flame to theprimary annular gutter 44 then a plurality of circumferentially spacedpilot burners may be provided in lieu of or in addition to said centralpilot burner with each of such circumferentially-spaced pilot burnerscommunicating directly with the primary annular gutter. Such anarrangement is illustrated in Figs. 5-7.

In Figs. 57, the parts corresponding to the parts of Figs. 1-4 have beenindicated by like reference numerals but with a subscript a addedthereto. The combustion apparatus of Figs. 5-7 is like that of Figs. 1-4except a plurality of circumferentially-spaced pilot burners 60 havebeen added and in addition a duct 62 has been provided upstream of eachlinear gutter 46a for conducting air to the associated pilot burner 60from the center body 18a. For this purpose, the center body 18a hasslots '63 through which the ducts 62 open into the center body 1801.Each pilot burner 60 has a conical upstream end and a pilot burner tube64 extend downstream therefrom. Each pilot burner 60 also has a fuelnozzle 66 for supplying fuel for mixture with said pilot burner air.Each pilot burner 60 also has a flame holder disc 68. If, asillustrated, a central pilot burner 26a is provided, then the auxiliarypilot burners 60 are ignited by the flame propagated from said centralpilot burner along the gutters 46a so that no special igniter means isnecessary for the auxiliary pilot burners. Each pilot burner tube 64 isinterposed in the annular gutter 44a thereby dividing said annulargutter into sections of V-shaped cross-section so that said tubes 64form part of said annular gutter. Thus each pilot burner tube 64 hassubstantially opposed V-shaped slots in its wall from which the adjacentV-shaped sections of the annular gutter extend. The apex of each saidV-shaped section of the gutter 44a at a pilot burner tube 64 is adjacentto the flame holder disc 68 of said tube and the sides of said V-shapedsections extend to the downstream end of said pilot burner tube wherebythe V-shaped sections of the annular gutter 44a also act as flamecross-over tubes for propagating a pilot flame from one pilot burner 60to the next for igniting said latter burner. This arrangement of aplurality of pilot burners with V-shaped gutters functioning as flamecross-over tubes is more fully disclosed in applicants co-pendingapplication Serial No. 219,047, filed April 3, 1951. The remainingstructure of Figs. 57 is essentially the same as that of Figs. 14. Itshould be noted that in Figs. 5-7 certain of the secondary lineargutters 50a extend downstream from the auxiliary pilot burners tubes 64while the remainder of said gutters 50a extend downstream from theV-shaped sections of the annular gutter 44a.

In both modifications illustrated, the jet engine has a centerbodystructure 18 or 18a. Such a centerbody structure, however, is notessential to a jet engine. If there is no such centerbody structure orif the air for the pilot burner or burners is not supplied through sucha centerbody structure then in order to supply said air it is necessaryto provide a duct or ducts extending upstream beyond the main fuelnozzles, for example as disclosed in said copending application.

While we have described our invention in detail in its present preferredembodiment, it will be obvious to those skilled in the art, afterunderstanding our invention, that various changes and modifications maybe made therein without departing from the spirit or scope thereof. Weaim in the appended claims to cover all such modifications.

We claim as our invention:

1. In combustion apparatus having a combustion chamber and means forsupplying a combustible mixture to said chamber; the combinationtherewith of means for igniting said main combustible mixture; saidigniting means comprising pilot burner means including a burner tubefrom which the pilot flame emanates; annular channel means co-axial withsaid pilot burner tube and disposed within said chamber for flow of saidmixture from a point upstream therefrom over the radially inner andouter annular sides of said annular channel means, said annular channelmeans having an open side facing downstream relative to said flow andhaving a diameter larger than the diameter of said pilot burner tube atits discharge end; and a plurality of linear channel members extendingfrom said pilot burner tube to said annular channel means and beingcircumferentially-spaced about the axis of said annular channel meansfor flow of at least a portion of said mixture therebetween, each saidlinear channel member having an open side facing in the direction of theflow over said member and the channel of each linear channel membercommunicating at one end with said pilot burner tube and at its otherend with the channel of said annular channel means.

2. In combustion apparatus having a combustion chamber and means forsupplying a main combustible mixture to said chamber; the combinationtherewith of means for igniting said main combustible mixture; saidigniting means comprising first annular channel means disposed withinsaid chamber across the flow path of said main combustible mixture forflow of said main mixture from a point upstream therefrom over theradially inner and outer annular sides of said annular channel means,said annular channel means having an open side facing in a downstreamdirection relative to said flow; pilot burner means having means forproviding its own combustion mixture and communicating with said annularchannel means for causing a pilot flame to extend into the channel ofsaid annular channel means; second annular channel means. disposedacross said flow path co-axial with and downstream of said first annularchannel means and having an annular open side facing in said downstreamdirection; and a plurality of linear channel members each having one endcommunicating with the channel of said first annular channel means andhaving its other end communicating with the channel of said secondannular channel means, said linear channel members diverging from eachother in said downstream direction and being circurnferentially-spacedabout the axis of said annular channel means for flow of at least aportion of said main mixture therebetween, the channel of each linearchannel member being open on its downstream side relative to .theadjacent main mixture flow between said members.

3. Apparatus as recited in claim 2 in which the divergence of saidlinear channel members is such that each linear channel member isinclined to the axis of said annular channel means by no more thanapproximately and in which at least the major portion of each annularchannel means and each linear channel member has a V-shapedcross-section with its apex on its upstream side.

4. In combustion apparatus having a combustion chamber and means forsupplying a main combustible mixture to said chamber; the combinationtherewith of means forigniting said main combustible mixture; saidigniting means comprising a pilot burner disposed in said chamber andhaving means for providing its own combustible mixture; first annularchannel means disposed within said chamber co-axial with and adjacent tothe discharge end of said pilot burner and disposed across the flow pathof said main combustible mixture for flow of said main mixture from apoint upstream therefrom over. the radially inner and outer annularsides of said annular channel means, said annular channel means havingan open side facing in a downstream direction relative to said flow andhaving a radius larger than that of the discharge end of said pilotburner; a first plurality of linear channel members extending from saidpilot burner to said first annular channel means, the channel of each ofsaid linear channel members communicating at one end with said pilotburner and at its other end with the channel of said annular channelmeans; second annular channel means co-axially disposed downstream ofsaid first annular channel means, said second annular channel meanshaving a larger radius than said first annular channel means and havingan open side facing in said downstream direction; and a plurality ofsecond linear channel members each having one end communicating with thechannel of said first annular channel means and having its other endcommunicating with the channel of said second annular channel means,each of said plurality of linear channel members beingcircumferentially-spaced about the axis of said annular channel meansfor flow of said main combustible mixture between said members and thechannel of each said linear channel member being open on its downstreamside relative to the adjacent main combustible mixture flow between saidsecond linear channel members.

5. Apparatus as recited in claim 4 in which said second annular channelmeans has an inner radius larger than the outer radius of said firstannular channel means and. said second linear channel members divergefrom each other in said downstream direction so that each second linearchannel member is inclined to the axis of said annular channel means byno more than 10.

6. Apparatus as recited in claim 5 in which at least the major portionof each said annular channel means and each said linear channel memberhas a V-shaped crossection with its apex on its upstream side.

7. Apparatus as recited in claim 4 in which said second annular channelmeans has an inner radius larger than the outer radius of said firstannular channel means and said second linear channel members divergefrom each other in said downstream direction so that each second linearchannel member is inclined to the axis of said annular channel means byapproximately 4 to 7.

8. Apparatus as recited in claim 7 in which said pilot burner includes aburner tube having an open discharge end of reduced diameter with saidopen discharge end facing in said downstream direction and with thedownstream end of said first annular channel means being disposeddownstream of said burner tube discharge end.

9. In combustion apparatus having a combustion chamber and means forsupplying a main combustible mixture to said chamber; the combinationtherewith of means for igniting said main combustible mixture; saidigniting means comprising first annular channel means disposed withinsaid chamber for flow of said main mixture from a point upstreamtherefrom over the radially inner and outer sides of said annularchannel means, said annular channel means having an open side facing ina downstream direction relative to said flow; a plurality ofcircumferentially-spaced pilot burners interposed in said annularchannel means, each pilot burner having means for providing its owncombustible mixture and having a burner tube with the open end of saidburner tube being directed in said downstream direction and with eachburner tube having a pair of slots in its side wall providingcommunication between said tube and the adjacent portions of the channelof said annular channel means; second annular channel means co axiallydisposed downstream of said first annular channel means, said secondannular channel means having a radius larger than said first annularchannel means and having an open side facing downstream relative to saidmain mixture flow; and a plurality of linear channel members each havingone end communicating with the channel of said first annular channelmeans and having its other end communicating with the channel of saidsecond annularrchannel means, said ,plurality of linear channel membersbeing circumferentially-spaced about the axis of said annular channelmeans for flow of at least-aportion of said main mixture between saidmembers and each linear channel member having an open side facing in thedirection of the adjacent main mixture fiow between said members.

10. Apparatus as recited in claim 9 in which the channel of each annularchannel means and each linear channel member diverges toward its openside and each pilot burner tube has flame holder means extendingthereacross inwardly of the open end of said tube and adjacent to theapex of the adjacent portions of the channel of said first annularchannel means and in which said linear channel members diverge in saiddownstream direction such that each linear channel member is inclined tothe axis of said annular channel means by no more than 10.

11. In a jet engine including a duct, a center body coaxially disposedwithin said duct and having a streamlined outer periphery, a combustionchamber within said duct downstream of said center body and means forsupplying a combustible mixture of air and fuel to said combustionchamber through the annular path about said center body; the combinationtherewith of means for igniting said combustible mixture for combustionin said chamber; said igniting means comprising a pilot burnerco-axially disposed within said streamlined center body, said pilotburner including a burner tube having an open discharge end in which thedischarge passage of said burner tube includes the entirecross-sectional area of the space between the outer walls of said tubeat said discharge end; means for supplying fuel and air to said pilotburner tube; and a plurality of circumferentially-spaced means extendingradially outwardly from said tube across the flow path of saidcombustible mixture for flow of said mixture thereover from a pointupstream therefrom, said lastmentioned means communicating with saidpilot burner tube for spreading the pilot burner flame outwardlytherefrom across said flow path.

12. In a jet engine including a duct, a center body coaxially disposedwithin said duct and having a streamlined outer periphery, a combustionchamber within said duct downstream of said center body, and means forsupplying a combustible mixture of air and fuel to said combustionchamber through the annular path about said center body; the combinationtherewith of means for igniting said combustible mixture in saidchamber; said igniting means comprising a pilot burner co-axiallydisposed within said center body and spaced from the surrounding wall ofsaid center body to provide annular passage means therebetween, saidpilot burner including a burner tube having an open discharge enddisposed at the downstream end of said center body and in which thedischarge passage of said burner tube includes the entirecross-sectional area of the space between the outer walls of said tubeat said discharge end; means for supplying fuel and air into said centerbody to said pilot burner tube, a portion of said air flowing outthrough said annular passage means about the pilot burner for coolingsaid pilot burner; and a plurality of circumferentially-spaced channelmeans each having an open channel side facing in a downstream direction,said channel means extending radially outwardly from said tube acrossthe flow path of said combustible mixture adjacent to the upstream endof said chamber for flow of said mixture over said channel means from apoint upstream therefrom, one end of said channel means communicatingwith said pilot burner tube for spreading the pilot burner flameoutwardly therefrom across said flow path.

13. In a jet engine including a duct, a center body coaxially disposedwithin said duct and having a streamlined outer periphery, a combustionchamber within said duct downstream of said center body, and means forsupplying a combustible mixture of air and fuel to said com- 8 bustionchamber through the annular path within said duct about said centerbody; the combination therewith of means for igniting said combustiblemixture in 'said chamber; said igniting means comprising a pilot burnerhaving a pilot burner tube co-axially disposed withinsaid center bodyand spaced from the surrounding wall of said center body to provideannular passage means therebetween, said pilot burner tube having adischarge-end of reduced diameter disposed at the downstream end of saidcenter body; means for supplying air into said center body to said pilotburner, a portion of said air flowing out through said annular passagemeans about the pilot burner tube'for cooling said tube; annular channelmeans having its open side directed in a downstream direction, saidannular channel means being co-axially disposed and extending downstreamof the discharge end of said pilot burner tube and having a radiuslarger than that of said discharge end; and a plurality ofcircumferentially-spaced linear channel members extending from saidpilot burner tube to said annular channel means, the channel of each ofsaid linear channel members communicating at one end with the pilotburner tube and at its other end with the channel of said annularchannel means and the open channel side of each linear channel memberfacing in a downstream direction.

14. In a jet engine including a duct, a center body coaxially disposedwithin said duct and having a streamlined outer periphery, a combustionchamber within said duct downstream of said center body, and means forsupplying a combustible mixture of air and fuel to said combustionchamber through the annular path within said duct about said centerbody; the combination therewith of means for igniting said combustiblemixture in said chamber; said igniting means comprising a pilot'burnerhaving a pilot burner tube co-axially disposed within said center bodyand spaced from the surrounding Wall of said center body to provideannular passage means therebetween, said pilot burner tube having adischarge end of reduced diameter disposed at the downstream end of saidcenter body; means for supplying air into said center body to said pilotburner, a portion of said air flowing out through said annular passagemeans about the pilot burner tube for cooling said tube; first annularchannel means having its open channel side directed in a downstreamdirection relative to the flow of said combustible mixture, said annularchannel means being co-axial with and extending downstream of thedischarge end of said pilot burner tube and having a radius larger thanthat of said discharge end; a first plurality ofcircumferentially-spaced linear channel members extending from saidpilot burner tube to said annular channel means, the channel of each ofsaid linear channel members communicating at one end with the pilotburner and at its other end with the channel of said annular channelmeans and the open channel side of each linear channel member facing ina downstream direction; a second plurality of circumferentially-spacedlinear channel members each having its channel communicating with thechannel of said first annular channel means said second linear channelmembers extending in a downstream direction from said first annularchannel means and diverging from each other such that each second linearchannel member is inclined to the axis of said pilot burner byapproximately 4 to 7 with its open side facing inwardly; and secondannular channel means coaxial with said first annular channel means andextending across the downstream ends of said second linear channelmembers with its channel communicating with the channel of each of saidsecond linear channel members, said second annular channel means havingits open side directed in said downstream direction.

15, In a jet engine including a duct, a center'body coaxially disposedwithin said duct and having a streamlined outer periphery, a combustionchamber downstream of said center body, and means for supplying acombustible mixture of air and fuel to said combustion chamber throughthe annular path about said center body; the combination therewith ofmeans for igniting said combustible mixture for combustion in saidchamber; said igniting means comprising a pilot burner co-axiallydisposed Within said streamlined center body, said pilot burnerincluding a burner tube having an open discharge end of reduced diameterterminating at the downstream end of said center body; first annularchannel means having its open side directed in a downstream direction,said annular channel means being co-axially disposed and extendingdownstream of the discharge end of said pilot burner tube and having aradius larger than that of the discharge end of the pilot burner tube; afirst plurality of circumferentially-spaced linear channel membersextending from said pilot burner tube to said annular channel means, thechannel of each of said linear channel members communicating at one endwith the pilot burner tube and at its other end with the channel of saidannular channel means and the open channel side of each linear channelmember facing in a downstream direction; a second plurality ofcircumferentially-spaced linear channel members each having its channelcommunicating at one end with the channel of said first annular channelmeans, said second linear channel members extending in a downstreamdirection from said first annular channel means and diverging from eachother such that each second linear channel is inclined to the axis ofsaid pilot burner by approximately 4 to 7 with its open side facinginwardly; and second annular channel means co-axial with said firstannular channel means and extending across the downstream ends of saidsecond linear channel members with its channel communicating with thechannel of each of said second linear channel members, said secondannular channel means having its open side directed in a downstreamdirection.

16. In a jet engine including a duct, a center body coaxially disposedwithin said duct, a combustion chamber downstream of said center body,and means for supplying a combustible mixture of air and fuel to saidcombustion chamber through the annular path about said center body; thecombination therewith of means for igniting said combustible mixture forcombustion in said chamber; said igniting means comprising a pilotburner co-axially disposed at the downstream end of said center body,said pilot burner including a burner tube; first annular channel meanshaving its open side directed in a downstream direction, said annularchannel means being co-axially disposed and extending downstream of thedischarge end of said pilot burner tube and having a radius larger thanthat of the discharge end of the pilot burner tube; a first plurality ofcircumferentially-spaced linear channel members extending from saidpilot burner tube to said annular channel means, the channel of each ofsaid linear channel members communicating at one end with the pilotburner tube and at its other end with the channel of said annularchannel means and the open channel side of each linear channel memberfacing in a downstream direction; a second plurality ofcircumferentially-spaced linear channel members each having its channelcommunicating at one end with the channel of said first annular channelmeans, said second linear channel members extending in a downstreamdirection from said first annular channel means and diverging from eachother such that each second linear channel is inclined to the axis ofsaid pilot burner by no more than approximately 10 with its open sidefacing inwardly; and second annular channel means co-axial with saidfirst annular channel means and extendacross the downstream ends of saidsecond linear channel members with its channel communicating with thechannel of each of said second linear channel members, said secondannular channel means having its open side directed in a downstreamdirection.

17. In a jet engine including a duct, a center body co-axially disposedwithin said duct, a combustion chamber within said duct downstream ofsaid center body, and

means for supplying a combustible mixture of air and fuel to saidcombustion chamber through the annular path about said center body; thecombination therewith of means for stabilizing combustion within saidchamber; said stabilizing means comprising means providing a shelteredchamber co-axially disposed at the downstream end of said center bodyand having an open downstream end; annular channel means having its openchannel side directed in a downstream direction relative to flow of saidcombustible mixture, said annular channel means 'being co-axiallydisposed downstream of said chamber and having a diameter larger thanthe diameter of the downstream end of said chamber; and a plurality ofcircumferentially-spaced linear channel members extending from saidchamber to said annular channel means, each of said linear channelmembers having the open side of its channel facing in said downstreamdirection and having its channel communicating at one end with saidchamber and its other end with the channel of said annular channelmeans.

18. In a jet engine including a duct, a center body coaxially disposedwithin said duct, a combustion chamber within said duct downstream ofsaid center body, and means for supplying a combustible mixture of airand fuel to said combustion chamber through the annular path about saidcenter body; the combination therewith of means for stabilizingcombustion within said chamber; said stabilizing means comprising meansproviding a sheltered chamber co-axially disposed at the downstream endof said center body and having an open downstream end; first annularchannel means having its open channel side directed in a downstreamdirection relative to flow of said combustible mixture, said annularchannel means being co-axially disposed downstream of said chamber andhaving a diameter larger than the diameter of the downstream end of saidchamber; a first plurality of circumferentially-spaced linear channelmembers extending from said chamber to said annular channel means, eachof said linear channel members having the open side of its channelfacing in said downstream direction and having its channel communicatingat one end with said chamber and its other end with the channel of saidannular channel means; second annular channel means having its openchannel side directed in said downstream direction, said second annularchannel means being co-axially disposed downstream of said first annularchannel means and having a diameter larger than the diameter of saidfirst annular channel means; and a second plurality ofcircumferentially-spaced linear channel members extending from saidfirst to said second annular channel means, each of said second linearchannel members having the open side of its channel facing in saiddownstream direction and having its channel communicating at one endwith the channel of said first annular channel means and at its otherend with the channel of said second annular channel means.

19. In a jet engine including a duct, a center body coaxially disposedwithin said duct, a combustion chamber within said duct downstream ofsaid center body, and means for supplying a combustible mixture of airand fuel to said combustion chamber through the annular path about saidcenter body; the combination therewith of means for stabilizingcombustion within said chamber; said stabilizing means comprising meansproviding a sheltered chamberco-axially disposed at the downstream endof said center body and having an open downstream end; first annularchannel means having its open channel side directed in a downstreamdirection relative to flow of said combustible mixture, said annularchannel means being co-axially disposed downstream of said chamher andhaving a diameter larger than the diameter of the downstream end of saidchamber; a first plurality of circumferentially-spaced linear channelmembers extending from said chamber to said annular channel means, eachof said linear channel members having the open side of its channelfacing .in said downstream direction and -havin1g its channelcommunicating at one end with said chamber andits other end with thechannel of said annular channel means; second annular channel meanshaving its open channel side directed in said downstream direction, saidsecond annular channel means co-axial with and axially spaced from saidfirst annular channel means and having a diameter larger than thediameter of said first annular channel means; and a second plurality ofcircumferentially-spaced linear channel members extending from saidfirst to said second annular channel means, each of said second linearchannel members having the open side of its channel facing in saiddownstream direction and having its channel communicating at one endwith the channel of said first annular channel means and at its '12other "end with the channel of saicl's'econdiannular channel means.

References Cited in the file of this patent UNITED STATES PATENTSBrzozowski Mar. 24, 1953

